The Myeloproliferative Disorders Research Consortium (MPD-RC) focuses on the Philadelphia chromosome negative myeloproliferative neoplasms (MPN) including polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF) and has the following goals 1) Establish a multi-institutional international research group which will coordinate and facilitate basic and clinical research dealing with the cellular and genetic basis of the MPN. 2) Establish a multi-institutional Clinical Consortium to enable uniform, high volume sample collection, storage and distribution. 3) Perform rationally designed clinical trials in patients with MPN at multiple institutions. 4) Maintain an interactive website for MPD Consortium investigators, a sophisticated international tissue bank and an on-line database that will allow for integration of basic and clinical research. This unique interactive relationship between talented basic researchers and clinical scientists will permit the MPD-RC to develop novel clinical treatment programs for MPN and to identify specific biomarkers that will be useful as indicators of therapeutic response and/or risk reduction. This program has six major projects: Project 1: Genetic Basis of Polycythemia Vera, Project Leader: J. T. Prchal;Project 2: A Novel Murine Model for MPN: Pathology and Therapy of NF-E2 Overexpression, Project Leader: H. L. Pahl;Project 3: Animal Models of Polycythemia Vera, Project Leader: J. L. Spivak;Project 4: Mouse Models of Myelofibrosis, Project Leader: A. Migliaccio;Project 5: Abnormal Stem Cell Trafficking in Myelofibrosis, Project Leader: R. Hoffman;Project 6: MPD Clinical Consortium which will pursue clinical trials in PV. ET and PMF, Project Leader: Lewis Silverman. The 6 projects will be supported by 3 cores: Core A, Administrative Core, PI: R. Hoffman;Core B: Biostatistics and Data Management;PI: J. A. Goldberg and Co-PI R. Marchioli;Core C;Tissue Bank, PI: R. Weinberg. These unique interactions between clinical and laboratory investigators which are interwoven within the MPD-RC will ultimately result in improved understanding of the pathobiology of the MPN as provide well improved strategies that will assist in the management of MPN patients.